docs: def write_markdown_to_file(self, f):
      """Writes this index to file `f`.
  
      The output is formatted as an unordered list. Each list element
      contains the title of the library, followed by a list of symbols
      in that library hyperlinked to the corresponding anchor in that
      library.
  
      Args:
        f: The output file.
      """
      print("---", file=f)
      print("---", file=f)
      print("<!-- This file is machine generated: DO NOT EDIT! -->", file=f)
      print("", file=f)
      print("# TensorFlow Python reference documentation", file=f)
      print("", file=f)
      fullname_f = lambda name: self._members[name][0]
      anchor_f = lambda name: _get_anchor(self._module_to_name, fullname_f(name))
  
      for filename, library in self._filename_to_library_map:
        sorted_names = sorted(library.mentioned, key=lambda x: (str.lower(x), x))
        member_names = [n for n in sorted_names if n in self._members]
        # TODO: This is a hack that should be removed as soon as the website code
        # allows it.
        full_filename = self._path_prefix + filename
        links = ["[`%s`](%s#%s)" % (name, full_filename[:-3], anchor_f(name))
                 for name in member_names]
        if links:
          print("* **[%s](%s)**:" % (library.title, full_filename[:-3]), file=f)
          for link in links:
            print("  * %s" % link, file=f)
          print("", file=f)